federated query in GCP big query with schema not working

Question

I am doing a POC to use bigquery's federated query feature. I have a Cloud Sql postgresql db. All tables are part of app schema. When I write a query like this it doesn't work.

SELECT
  *
FROM
  EXTERNAL_QUERY("xxxx.us.xxxx",
    "SELECT * FROM app.meeting;");

If I use public schema table which I added for testing purpose then it works both way.

SELECT
  *
FROM
  EXTERNAL_QUERY("xxxx.us.xxxx",
    "SELECT * FROM public.sampletable;");

OR

SELECT
  *
FROM
  EXTERNAL_QUERY("xxxx.us.xxxx",
    "SELECT * FROM sampletable;");

What is the right way to use schema which is not public.